Production of anthraquinone dyestuffs



Patented July 16, 1929.

UNITED STATES PATENT OFFICE.

DONALD G. ROGERS, OF HAMBURG, NEW YORK, ASSIGNOR '10 NATIONAL ANILINE & CHEMICAL 00., INC., OF NEW YORK, N. Y., CORPORATION OF NEW YORK.

PRODUCTION OF ANTHRAQUINONE DYESTUFFS.

No Drawing.

This invention relates to improvement-s in the manufacture and production of diaminodihydroxyanthraquinone monosulfonic acids from diaminodihydroxyanthraquinone disulfonic acids, particularly diaminoanthrarufine monosulfonic acid from diaminoanthrarufine disulfonic acid and diaminochrysazine monosulfonic acid from diaminochrysazine disulfonic acid.

It is well known that by reducing diaminoanthrarufine disulfonic acid, or .diaminochrysaz'ine disulfonic acid, with suitable reducing agents under proper conditions, a sulfo-group can be eliminated and leuco-com pounds formed which upon subsequent oxidation produce the corresponding diaminodihydroxyanthraquinone monosulfonic acids.

The present invention relates to an improved process for producing such monosulfonic acids from the disulfonic acids.

'According to the present invention, diam? inoanthrarufine disulfonic acid or diaminochrysazine disulfonic acid, or a mixture of these acids, is subjected to reduction by the action of zinc dust in the presence of sodium bisulfite and the leuco-compounds of the monosulfonic acids thus produced are sub sequently subjected to the action of suitable oxidizing agents in order to obtain the monosulfonic acid of diaminoanthrarufine or of diaminochrysazine, or a mixture of the same. The invention readily efi'ects the'production of a leuco-compound of the monosulfonic acid from the disulfonic acid with minimum formation of undesirable by-products, the operating conditions are readily controlled, and the yield and purity of the final product is excellent.

In carrying out the present invention, it is not necessary to start from the dia nino disulfonic acids themselves but the corresponding dinitro disulfonic acids of anthrarul-z'ne or chrysazine may be used as the iniialmateriaL and the production of the leuco-compounds of the corresponding diamino monosulfonic acids can be effected in one operation.

Mixtures of the diamino disulfonic acids of anthrarufine and chrgsazine, or mixtures of their corresponding initro compounds, can be employed without altering thereby the process of the'present invention.

The invention will be further illustrated by the following specific example, but it is ungpplication filed May 5, 1924. Serial No. 711,047.

derstood that it is not limited thereto. he parts are by weight.

Example: 1280 parts of a 50 percent paste composed of a mixture of the sodium salts of dlaminoanthrarufine disulfonic acid and diaminochrysazine disulto'nic acid are suspended in 12,800 parts of water at about 30 Q. and the mixture neutralized by the additron of sulfuric acid of about 30-35 percent strength. 265 parts of powdered sodium bisulfite (100% purity or its equivalent) are added, and to the well-stirred mixture about 125 parts of zinc dust (100% purity or its equivalent) in the form of a thin aqueous paste or slurry are then added over a period of about 10 to 20 minutes. The mixture is vigorously agitated at about 30-35 C. for about 20 to 35 minutes, or until a test sample which has been reoxidized with air in the presence of caustic soda is completely insoluble, or nearly so, in dilute sulfuric or hydrochloric acid'. If necessary,-more sodium bisulfite and zinc dust may be added to complete the reduction. When the reduction is complete, the solution containing the leucodye in suspension is separated from excess zinc, if any is present, by centrifuging,decantation, or other suitable method. Common salt is then added to the solution and the precipitated leuco-dye isolated by filtration, or the solution is made alkaline by the addition of caustic soda, and air blown through it for six or'eight hours at about 50 (3., or until the oxidation is complete. During the oxidation, a major part of the monosulfonic acid will be separated in the shape of theirsodium salts which may contain small amounts of zinc compounds or salts. When the oxidation is complete, the sodium salts are either isolated by filtration or the mixture is acidfied by the addition of sulfuricor hydrochloric acid and ployed in a suitable manner, as is well known, to oxidize and transform the leuco-compounds into the corresponding monosulfonic acids.

In, the above example, the procedure may be'modified as follows: To 1280 parts of 50 percent paste comprising a mixture of the diamino' disulfonic acids of anthrarufine and chrysazine suspended in 12,800 parts water at about 30 C. and neutralized with sulfuric acid, there is added, with good stirring,-- 53 to 55 parts of sodium bisulfite and 125 parts zinc dust. After a period of 10 to 15 minutes,

sulfuric acid of about 30 percent strength is slowly added to the well stirred mixture until the odor of sulfur dioxide can be just detected. Excess of sulfuric acid over that just required to convert the neutral sulfites into acid sulfites, that is, into bisulfites, mustbe avoided since the presence of free or uncombined sulfuric acid gives rise to low yields and a poor quality of product. After a short time the odor of sulfur dioxide disappears and then a further amount of sulfuric acid is slowly added until sulfur dioxide can be again just detected. Thisoperation is repeated until a test shows tha'tthe reduction of the diaminodisulfonic acid to a leuco-compound of the monosulfonic acids is complete. From this point, the process is completed as described in the first example.

Instead of adding the sulfuric acid in steps, it may be added moreor less continuously at such a rate as to maintain the presence of bisulfites throughout the reduction, care being taken to avoid the presence of free or uncombined sulfuric acid. Additional amounts of zinc dust may be added during the process if found necessary for the completion of the reduction. By this procedure, the neutral or normal sodium sulfite and zinc sulfite formed during the reduction by the action of zinc and sodium bisulfite are converted by the sulfuric acid into their acid sulfites, that is, bisulfites, which in turn react with further quantities ofzinc. In this way, the amount of sodium bisulfite initially employed in the reaction need be only about one-fifth, or .even less, as much as that required when no sulfuric acid is used. At the completion of the reduction, nearly all of the zinc and zinc compounds are in solution.

In an analogous manner, diaminoanthrarufine disulfonic acid and diaminochrysazine disulfonic acid maybe each separately reduced to the leuco-compounds of the corresponding monosulfonic acids which can be subsequently oxidized to the monosulfonic acids.

In the specification and claims, it will be understood that the terms diaminodihydroxyanthraquinone disulfonic acids and diaminodihydroxyanthraquinone monosulfonic acids refer to and include the disulfenic acids and their salts and the monosul-- the amount of sodium bisulfite employed is only a small fraction of the amount used when no sulfuric acid is employed. In the absence of sulfuric acid, the reduction may be regarded as based on the following equation:

Upon the addition of sulfuric acid, the zinc sulfite and sodium sulfite produced according to the above equation are regarded as being converted into zinc sulfate and sodium bisulfite as represented by the equation:

As a result of adding an acid during the process, the amount of sodium bisulfite during the reduction remains substantially constant and equal to the amount initially employed.

I claim:

1. The process of making a leuco-compound of a diaminodihyd'roxyanthraquinone monosulfonic acid, which comprises subjecting a diaminodihydroxyanthraquinone disulfonic acid to the action of zinc and sodium 'bisulfite. v

2. The process of making a leuco-compound of a diaminodihydroxyanthraquinone mono sulfonic acid, which comprises treating a diaminodihydroxyanthraquinone disulfonic acid with zinc and sodium bisulfite and adding theretofduring the treatment, sulfuric acid in amounts sufficient to maintain the presenceof a bisulfite during the reaction.

3. The process of making a diaminodihydroxyanthraquinone monosulfonic acid, which comprises the process claimed under claim 1 and the subsequent treatment of said 'leuco-compound with a suitable oxidizing agent, whereby a diaminodihydroxyanthraquinone monosulfonic acid is produced.

4. The process of making a diaminodihydroxyanthraquinone monosulfonic acid in the form of its alkali metal salt, which comprises subjecting a diaminodihydroxyanthraquinone disulfonic acid to reduction by the action of zinc and sodium bisulfite and, without isolation, subjecting the reduction product thus obtained to oxidation bv the action of atmospheric air in the presence of caustic alkali. i

5. The process of making a diaminodihydroxyanthraquinone monosulfonic acid in the form of its alkali metal salt, which comprises subjecting a diaminodihydroxyanthraquinone disulfonic acid to reduction by the action of zinc and a small amount of sodium bisulfite and adding to the reaction mixture during the reduction an amount of sulfuric acid suflicient to convert the sulfite present into bisulfite, and without isolation subjecting the reduction product thus obtained to oxidation by the action of atmospheric air in the presence of caustic alkali.

6. The process of making a leuco-compound of paradiaminoanthrarufine monosulfonic acid, which comprises subjecting paradiaminoanthrarufine disulfonic acid to reductfziion by the act-ion of zinc and sodium bisul- 7. The process of making a leuco-compound of paradiaminoanthrarufine monosulfonic acid, which comprises subjecting paradiaminoanthrarufine disulfonic acid to reduction by the action of zinc and sodium bisulfite, and during the reduction adding sulfuric acid in quantities suflicient to maintain the presence of bisulfite during the reaction.

8. The process of making an alkali metal salt of paradiaminoanthrarufine monosulfonic acid, which comprises subjecting paradiaminoanthrarufine disulfonic acid to reduction by the action of zinc and sodium bisulfite, and without isolation subjecting the product thus obtained to oxidation by the action of atmospheric airin the presence of caustic alkali.

9. The process of making an alkali metal salt of paradiaminoanthrarufine monosulfonic acid, which comprises subjecting para diaminoanthrarufine disulfonic acid to reduction by the action of zinc and a small amount of sodium bisulfite and adding during the reduction a suiiicient amount of acid to maintain the presence of. bisulfite, and without isolation subjecting the product thus obtained to oxidation by the action of atmospheric air in the presence of caustic alkali.

10. In the production of a leuco-compound of diaminodihydroxyanthraquinone mono-' sulfonic acid by subjecting diaminodihydroxyanthraquinone 'disulfonic acid to the action of zinc and sodium bisulfite, the step comprising the addition, during the reaction, of sulfuric acid in an amount suflicient to maintain the presence of bisulfite.

11. In the production of a leuco-compound of paradiaminoanthrarufine monosulfonic acid by subjecting diaminoanthrarufine disulfonic acid to reduction by means of zinc and sodium bisulfite, the step characterized by adding, during the reduction,..,an amount of sulfuric acid suflicient to maintain the presence of bisulfite.

12. Inthe process of replacing a sulfonic group in a diaminodihydroxyanthraquinone disulfonic acid by an atom of hydrogen, the improvement which comprises subjectin the diaminodihydroxyanthraquinone disul onic acid to the action of zinc in the presence of sodium bisulfite.

13. The process of eliminating one sulfonic acid group from a diamino-dihydroxyanthraquinone-disulfonic acid, ,which comprises subjecting :the diamino-dihy droxyanthraquinone-disulfonic acid to the action of zinc and sodium bisulfite, the amount of bisulfite initially employed being insufiicient to react with all of the zinc and adding from time to time to the reaction mixture an amount of sulfuric acid suflicient to form -time to time to the reaction mixture sulfuric acid in amounts sufficient, but not in excess, to form bisulfite from the sulfite present.

15. The process of making a diaminodihydroxy-anthraquinone monosulfonic acid, which comprises subjecting a diaminodihydroxyanthraquinone disulfonic acid in the presence of water to the action of zinc and an alkali metal bisulfite, separating the solution containing the leuco-compound of the monosulfonic acid thus obtained from any free zinc present, adding suflicient caustic alkali to the solution to render it alkaline and subjecting it to the action of a current of air whereby the leuco-compound is oxidized to the dye, and then acidifying the mixture and isolating the dye.

16. In the'production of a diaminodihydroxy-anthraquinone monosulfonic acid by subjecting a diaminodihydroxyanthraquinone disulfonic acid to reduction with formation of a leuco-compound of the monosulfonic acid'and subsequent oxidation of the leuco-compound to the dye in alkaline media, the improvement which comprises acidifying the alkaline solution containing the dye prior to its isolation therefrom.

17 The process of making a diaminodihydroxyanthraquinone monosulfonic acid in the form of its alkalim-etal salt, which comprises subjecting a diaminodihydroxyanthraquinone disulfonic acid to reduction by the action-of zinc and a small amount of an alkali metal bisulfite and adding to the reaction mixture during the reduction a suflicient amount of acid to maintain the presence of bisulfite.

18. The process of making an alkali metal salt of paradiaminoanthrarufin monosulfonic acid, which comprises subjecting paradiaminoanthrarufin disulfonic acid to reduction by the action of zinc and asmall amount of sodium bisulfite and-adding during the reduction an amount of sulfuric acid sufficient to convert the sulfite present into bisulfite.

In testimony whereof I affix my signature.

DONALD (3. ROGERS. 

